Bump download-artifact to v4

Author: maresb

.github/workflows/test.yml

@@ -273,7 +273,7 @@ jobs:
           python -m pip install -U coverage>=5.1 coveralls
 
       - name: Download coverage file
-        uses: actions/download-artifact@v3
+        uses: actions/download-artifact@v4
         with:
           name: coverage
           path: coverage